Whenever I read stories about babies being delivered when the mother had no idea she was pregnant I am dumbfounded. HOW? How can you not know? Where do they hide? Don’t you get cankles? How do you explain the sudden desire for peanut butter on everything?

Well, it’s happened again. Trish Staine, an aspiring marathon runner in the USA, says she had no idea she was pregnant before Monday’s surprise birth. The mother of three said she hadn’t gained any weight or felt fetal movement in the months before. And besides, her husband had a vasectomy.

How did she find out?

Trish was training hard for an upcoming half-marathon (go Mumma!) and put her back pain down to a two-hour training session she had in preparation. Remember, this is a mum of three, she must have really had no idea to not recognise labour pain!

“I had a sore back Sunday evening. I had taken a hot shower and was dealing with it,” Staine said. “Monday morning, I woke up and had more back pain, and as the day went on it got worse. I thought I should go to the ER. I thought I ruptured a disc or pulled a muscle.”

But the supermum soldiered on, watching her hubby play a game of basketball and attending her daughter’s play. When a bath at home did nothing for the pain, her husband called an ambulance.

“I felt like I was dying. I didn’t know what was going on,” she said.

During the emergency room examination, lo and behold, a fetal heartbeat was detected and the Trish was whisked into the delivery room where she was soon to meet a gorgeous 2.9kg surprise daughter!

What about the vasectomy?

Hold the phone. Didn’t Daddio have the snip? He did, but did you know that very rarely, the 2 cut ends of the vas deferens can join together and form an open channel for sperm again! Yowsers, that sperm means business.

And the mum, how does she not know?

I’ve had three kids, well before I was full term I couldn’t see my toes. How do these mums not know? There can be a few reasons:

A false pregnancy test: Home pregnancy tests can give false readings if used improperly, read wrong or taken too early.

Your body weight: Since each person carries weight differently, some women look quite large around the midsection during pregnancy whereas others barely show signs at all. A mother-to-be’s body weight before becoming pregnant can determine whether she and others notice. In addition, women who start a diet or begin an exercising regimen soon after becoming pregnant may not gain a noticeable amount of weight. The weight they lose might negate the pregnancy weight they gain.

You miss the side effects: Women who don’t know they’re pregnant until they’re in labour may confuse the side effects of pregnancy with other problems, including stress, food poisoning or indigestion.

Irregular menstrual cycles: Women who don’t know they’re pregnant until they enter the delivery room may have a history of irregular menstruation cycles; for them, missing a period or randomly experiencing spotting could be the norm.

Stress: Immense pressure and distress can push even the healthiest of women to deny the reality of pregnancy. Research has shown that stress can induce denied pregnancies in women who have no history of psychological problems

Believing you or your partner is infertile: Fertility issues can also influence whether a woman knows she’s pregnant, as can believing that procedures such as vasectomies are 100 percent safe. Even thinking you’ve already experienced menopause can get in the way of realising you’re pregnant.

Mental health: It’s important to know that some (not all) women who experience denied pregnancy have underlying mental health problems that may get in the way of realising they’re pregnant.

Inactive bubba: Whether the baby rests in such a way that makes its movements hard to detect or it’s simply less active than others babies, movement in the womb, or lack thereof, can cause a woman to miss the fact that she’s pregnant.

Overconfidence in contraceptives: This explains why women who don’t know they’re pregnant until they’re in labour are often in shock over their situation.

Mistaking symptoms: Women with a history of ovarian complications such as tumors or cysts may attribute discomfort or pain to their existing condition.

So there you have it. It is possible to be up the duff and really not have a clue. The fact that this active mum of three had no idea just goes to show how sneaky our bodies can be (and in her case, how determined her husband’s sperm is). Looking at these pictures, it’s clear to see that there are many worse surprises in life than a gorgeous newborn!